Updated

South Sudan is softening its rejection of a regional protection force a day after the U.N. Security Council voted to deploy 4,000 additional peacekeepers.

But a government spokesman says it will accept the force only if it can negotiate the size, mandate, weapons and contributing countries.

Presidential spokesman Ateny Wek Ateny said Saturday that "the door is open" but would not say whether South Sudan has dropped its objection to the force answering to the existing U.N. peacekeeping mission.

The spokesman also says neighboring Uganda, Sudan, Ethiopia and Kenya cannot take part.

An outbreak of fighting in the capital, Juba, saw civilians, aid workers and U.N. staffers come under attack.

South Sudan government officials have been vague about how they will respond if the new protection force enters uninvited.